Oxyalkylene polymers containing a silicon-containing group in which hydroxyl groups and/or hydrolyzable groups are bonded to the silicon atom (hereinafter sometimes referred to as a reactive silicon group) and which are thereby capable of crosslinking through siloxane bond formation are disclosed, e.g., in U.S. Pat. No. 3,971,751. Representative of such oxyalkylene polymers is a polymer of the formula: EQU X'.sub.3 Si(oxypropylene polymer)SiX' .sub.3
wherein X' represents a hydrolyzable group such as a methoxy group.
Oxyalkylene polymers having a reactive silicon group are cured through formation of a siloxane bond (Si--O--Si) among polymer molecules by the action of moisture in the air and the like at room temperature similar to room temperature curable silicone rubbers to thereby provide a rubbery cured product. The cured product of the oxyalkylene polymer has excellent tensile characteristics, such as large elongation, low modulus and high breaking strength, excellent adhesive properties, and excellent printability on the surface of the cured product and are therefore useful as sealants, adhesives and the like.
While the cured product of the oxyalkylene polymer having a reactive silicon group exhibits superior performance properties as described above, it is often required to have a low modulus when used as a sealant and the like. Although almost all paint can be applied on the surface of the cured product, so-called alkyd paints are hardly dried and cured when applied on the surface the cured oxyalkylene polymer. Moreover, since the surface of the cured product is liable to pick up dust to produce an impaired appearance, it is sometimes unsuitable for use as a sealant or a coating.
The inventors have previously proposed a composition capable of providing a cured product having a low modulus which comprises an oxyalkylene polymer having a reactive silicon group and a compound containing one silanol group per molecule and/or a compound capable of forming a compound having one silanol group per molecule on reacting with moisture (hereinafter inclusively referred to as a monosilanol compound), as disclosed in U.S. Pat. No. 4,788,254 (corresponding to JP-A-61-34066). It was determined, however that the cured product of this composition tends to be inferior to those of compositions containing no such monosilanol compound in terms of paintability of alkyd paints applied to the surface of the cured product and dust resistance.